High pressure steam generator



5 Shafts-Sheet 1 Aug. 4, 1931.

Figi.

Aug. 4, 1931. w. G. NQACK 1,817,419

HIGH PRESSURE STEAM GENERATOR Filed April 9, 1928 5 Sheets-Sheet 2Fig.2. 43 411154??? N Aug. 4, 1931. w. G. NoAcK HIGH PRESSURE STEAMGENERATOR Aug. 4, 1931. w. 5, NoAcK HIGH PRESSURE STEAM GENERATOR FiledApril 9. 1928 5 Sheets-Sheet 4 Aug. 4, 1931. w, G, NQACK 1,817,419

HIGH PRESSURE STEAM GENERATOR f 777W@ ff@ M.

Patented ug. 4, y1931 UNITED STATES ,PATENT OFFICE WALTER GUsTAV NoAcx,F BADEN, SWITZERLAND, YAssIeNoR To AKTIENGESELI; Y soHArT BROWN, BovERIa CIE., or KBADEN, SWITZERLAND HIGH PRESSURE STEAM GENERATOR Applicationfiled April 9, 19278, Serial No. l268,493, and in Germany andSwitzerland April l14, 1927,

It has yalready been .proposedto lgenerate steam by superheating steamand passing the ,superheated steam through a layer of water or.injecting finely divided water into .j 5 the same. Fresh steam is ,thengenerated by the transmission .of the heat .of superheat. It has furtherbeen'proposed topass superlieated steam several times through water .andto ysuperheat the steam freshly l1o generated .each timeand thepreviously generated Y steam *whichy has been cooled down bybeingpassedl throughthe layer yof water, until finally the requiredquantity of working steam has been generated.

l For overcoming the resistance ,of the superheaters vand that of theload of water and to bring the steam `in-to circulation, variousexpediente are required which entail certain disadvantages. If, forinstance, the steam be generated in a lsingle heat exchange body, it isnecessary toprovde a separate pump for circulating the steam which actsas the heat carrier and for various reasons must be many times the,quanltity of useful steam, whchpump requires a relatively large amountof kenergy `and vdetrimen-tally` affects the efiiciency of the plant toaconsiderable extent through the unavoidable leakage losses. If, on theother generating in a separate boiler so-called exciter steam at vahigher pressure andby allowing the said exciter steam to fiow with itsown 4drop lin pressure successively through several superheaters 'y andwater spaces, .fresh steambeing generated in each `Water space by theheat of superheat, vthe hcirculating pump becomes superfluous, it. is

true, butv a larger number ofl pressure .con-V tainfers becomesnecessary which. increase the cost of the plant, require more space andintroduce certain working difficulties..`

- The present invention relates to a method.

.of producing steam, more particularly high y Quantity et .steam thanhalf the .quanhand, motion be imparted to the steam by tity `of workingsteam) lis generated, which flows under its `own drop y in ressurethrough a lconsiderable number o super- :lieaters yor groups-ofsuperheaters located `one behind'the other', which are'prov'idedf atany number of points, but at least two points, -with devices, by meansof .which water is introduced in a finely divided state. By withdrawingthe superheat, fresh steam is generated `from the introduced water,which steam is superheated together with the now saturated,` previouslygenerated steam and so on until the desired quantity ofworking steam 'isobtained. i Figure l shows diagrammaticaljly the arfjg, .rangement ofthe steam' generator according tothe invention.

Figure 2 is a diagrammatic; section through the evaporator and the steamand i water collector with the water injector '7b' pump. 4 Figure 3shows the section throughr an evaporator with filling bodies forVinc-reasing the water-surface. f f 7 Fig-ure 4 the saine with fillingbodies to a'ct as water separators.

Figure 5' the arrangement of the evaporators witha device for injectingaddition water, y

ythe steamgenerator with pump for the injection water and a' heat pump,through which the exciter steamv can be generated (instead of theexciter steam boiler). j

In Figl of theaccompanying drawings the steam generator isshoWndiagram-mati- .cally tor carrying outthe method. In this figure, lis the furnace space. In this space is the exciter boiler Qand 3 linwhich thesmall quantity of exciter steam lis produced and the remainderof the feed water may j be preheated; l The vexciter steam Hows thenceunder its ,own pressure` through the pipes 6 by way of a throttlingpoint 29 and a shutting off valve 33 to thefirst superlieater 7, `ishighly -superheated in the said superheater and passes to thefirstevaporator 13, where the heat of superheat is with l.drawn trom it byinjected water which has ,y

abeen preheated --almost upto evaporation Figure 6 diagrammaticalvarrangement ofso f esr telnperature. By this superheating heat freshsteam is generated from the injected water, which steam together withthe exciter steam which has been cooled down to approximately saturationtemperature flows to the next superheater 8. Fresh superheating heat issupplied to this superheater, which enables an increased quantity ofsteam to be generated in the next evaporator 14 from the Water'injectedinto the steam. This is repeated until finally the required quantity ofworking steam is obtained.

The water to be injected can, as already stated above, be withdrawn fromthe exciter boiler 2, 3 lying in the furnace space, which therefore inthe present instance also acts as water heater, through the pipe 5 byway of a shut-off valve 32. The fresh water itself is introduced yat li.The whole of the steam generated leaves the last evaporator 18 by way ofthe valve 31 and passes through a final superheater 28, where it isbrought up to the degree of superheat required for working purposes, tothe `place where it is to be used. The other parts shown in Fig. l andnot hitherto described will be alluded to later on.

While Fig. l shows diagrammatically the steam generator seen from above,Fig. 2 shows the evaporator part with the container diagrammatically inside elevation partly in section. 13 to 18 are the evaporators whichreceive their injection water Athrough the pipe 5 for instance from thewater preheater of the exciter boiler (not seen in this Figure). Thewater is injected through nozzles i0 in a finely divided state, so thatit offers a large surface to the superheated steam entering at 4l., At42 wire sieves are vprovidedvwhich hold back large drops and cause themto be divided up and evaporated. The cooled an freshly generate steamleaves the evaporators at 43, whence it Hows to its particularsuperheater. In front of the outlet parallel sheet metal members may beprovided, on which any witer which may be carried along separates o Theobject of injecting in a very finely divided state is, as alreadystated, to present large surfaces for making a rapid absorpv tion ofheat possible. Instead of injecting in a finely divided state throughnozzles the spreading of the water to be evaporated over a large surfacemay be effected for instance by `suitable iliing pieces provided intheevaporatingbodies. This expedient has the advantagethat in place of anozzle of small bore ordinary roses can be used, which are `less liableto become stopped up, and thatthe carrying along of drops is morereadily prevented. These filling piecesfmay consist` of small cylinders(so-called yRaschig-rings) Vand are made of a material which is ay verygood heat conductor. In

Figs. 8 and 4t evaporators of this kind are shown in section. 50 is thebody of the evaporator, 5l are filling pieces. They rest on a grid 52below which the superheated steam is admitted at 58. The water entersthrough a rose 54; and is distributed over the filling pieces, wherebyit presents a largersurface to the steam meeting it in counterflow. Thecooled and freshly generated steam'flows off at 55 while superfluouswater is drained at 56.

The constructional form shown in F 4; differs frornthat of Fig. 3 inthis, that the filling forms two layers 5l and 57, having a free spacebetween them, into which the rose 54 opens. Thus, only the lower part isplayed on, the upper part acting 'as a steam and water separator. Inaddition it may be heated by the admission of superheated steam' fromthe pipe 53 or 58, so that any adhering drops will be evaporated.

It is important that the steam generator nder discussion should alwaysbe operated in such a manner that the iinal temperature of thesuperheating in each separate superheater and the quantity of waterinjected bear a certain relation to one another. I/Vhen too little wateris supplied, the consequence will be that the steam introduced is cooledoff too little and will be superheated too strongly in the nextsuperheater. Too much water on the other hand has the disadvantage thatwater may easily be carried along and any impurities may be deposited inthe super-heater tubes, rendering the latter foul. Another disadvantagemay be that unnecessary pumping worlr has to be performed. @ne possiblemanner ofA regulation is pro- `vided by the temperature of thesuperheated steam itself. For instance, a thermostat may be providedwhich is influenced by the temperature of the steam at any point, moreparticularly the temperature at the end of the super-heater following aninjection nozzle orgroup of nozzles. In Fig. l the arrangement of such amethod of regulation by a thermostat is shown. In this `ligure 19-23represent thermcstats of any known constructional form which act oncut-oit devices of any kind for the water supply pipes of theevaporators iii- 18. If the temperature at the end of asuperheater betoo high a thermostat operates the inlet `vaive in such a manner thatmore water will certainamount'may be introduced.y Thus,

for instance, the thermostat regulation vmay caused to act onV only apor-tion of the waterv supply, by providingV two' injection f nozzles orrosesV ortwo groups of thesame for eachevaporator, one of which suppliesthe injection water to be evaporated in normal working, while thevother, which is operated by a thermostat orl thelike, comes intooperation only in exceptional cases.r Such vexceptional cases may beeither `loads -eX- is in this instance, however, so regulated that apredetermined quantity of water fiows to it, which remains constantovera wide working range. The water which kdoes not evaporate flows awayat 56. Should the water introduced through the roses 54 be'for anyreasoninsufticient, so that in the subsequent superheater 60 or 61 thesuperheating eX- ceeds an admissible amount, the thermostat at 62 or 63becomes operative and automati- V cally opens the valve 64, 65 whichallows more water to How in until` the superheating temperature has sunkagaink to the predeterminedmaximum amount;` y

Should it not be possible to' evaporate all the injected water at onceor if the water be Vpurposely injected in eXcess, arsmaller or largerv.quantity of water' will accumulate in the bottomfo'f the evaporator.This water contains considerable quantities of energy in the formV ofheat and pressure. It'v is therefore of particuiar limportance that itshall be, taken away and .collectedfwithout loss. Thus, a furtherobjectof theapresent 'invention isv toprovide amethod of conveying awaylthis excesswater fromthebodies in which the injection and evaporationtakes place through lsuitable-,devices and of collecting it foi-furtheruse. For this purpose the ifaporatorbodies may be provided in theirlower parts with a small collecting space which is connected'with alarger collecting drum common to all the evaporators. This connection isby way of a floatioper'- ated valve or by a trapr' VThe lattermust be sovdesigned that while suilicient water vcan flow out, thep'assage oflarge quantities of stcam,for instance form one, evaporatorto the non,is prevented.` The c'oinmon collectingv drum is represented-in Fig.. 1as the drum 25, and they common outflow pipe by 24. In Fig. 2, 45 larethe traps which @pesimo the @needing @para The com;

tions ofthe pump has mon collecting drum is yshown in section-at 47. InFig. 5 the outlets 56 are shown but notvthe collecting' pipe and thedrum.

Thev collecting'drum in which the excess injection water is collectedmayse'rve a furtherpurpose. l It can also be used as a steam collectoror a buffer vessel for equalizing the fluctuations in the steamconsumption. If the superheaters and the evaporators in the new steamgenerator be regarded as corresponding in their action to the watertubes of ordinary steam generators, the accumulator represents the upperand `lowerdrums of. ordinary boilers, that is the parts by means ofwhich the water to be evaporated and the already generated steam can bestored. Through the last evaporator 18being connected as shown in Fig. lby the Vpipe the .othery handy the last superheater 28 is connected withthe steam4v dome 27, steam may, when there is a momentary excess ofsteam, be passed into the Water space of the drum 25 and be condensedthere with an increase in pressure. is a momentary lack of steam,.steammay be withdrawn at l27 fromk the drum, the pressure iny the drumdecreasing. The Water which was injected in excess into 'the heatexchange bodies (evaporators)" and passed away to the drummay be usedagain `Wholly or in part for injection purposes. vFor this purpose itmust be brought up to the requisite injection pressure by a pump.

Conversely, when there li "34 with the distributor pipe.v 26, While on fThis mode of operation isshown in the dia- .5100

grammatic view in Fig.' 2, in which 46 represents the pipek forconveying away the excess of' water and y47 the drum, whilethe pumpreferred'tois shown at 48 'and the moto'r vforfdriving it, forinstancean electric 'i motor at 49.V The suction pipe of thepump -isconnected to theldrumand the delivery pipeleads to the evaporators'134-18 which mayalso be fed by the pipe 5 fromthe eX-l citerboiler.-.-When theginjection water is delivered entirely by'l-waterwhich the pump 48 has withdrawn from the drum, the valve 70 is closedand the feed water rwhich vhas been preheatedin the exciterqboiler korfresh feed water is delivered directly through the 115 pipe 71 to thedrum. In this case-a float-operatedvalve 72V is required which'regulates the water level in the drum `47. Y

The pumpl 48 may with advantage vbe drivenby a steam turbine 7 3.` Forensuring reliable working, in addition to the steam turbine an electricmotormay be ycoupled up as Well, which runs idle and is only supplied cwith current when the number of revoluf sible amount.` f H For ensuringreliable yWorking and the sunk below ,an admisyproper functioning of thenew steam igen# e-rator, variousdetailsare required which tion. Thus,the heat exchange bodies (evaporator bodies) must be provided With mudseparators. Furthermore it may be necessary more particularly when theWater is introduced in a linely divided stateby means of injectionnozzles, that the injection water shall have a considerably higherpressure than the steam. When the exciter steam and the injection Waterare delivered from the same boiler, for instance as shown in Fig. l at 2and 3, in other Words, When the Water and the steam are at the samepressure, the pressure of the steam must be artificially reduced for theevaporators. This may be efected hy a reducing valve, indicated by Wayof example in Fig. l at 29.

From the manufacturing point of view it is an advantage for all theparts used to have the same dimensions. This can be effected by all thesuperheatcr parts having the same surface and being grouped about thefurnace and in the flues in a similar manner. Furthermore, all thesuperheaters or superheater groups may be arranged one behind the otherin such a manner, and their superficial area and the cross-sectionalareas of the steam passages may be made such, for instance by placingseveral superheater parts in parallel, that for each superheater orgroup of Asuperheaters the evaporator bodies and the injection nozzleswill be of the same size and construction.

The new steam generator provides the further great advantage that theboiler parts containing considerablequantities of Water and steam, asfor instance the exciter boiler and the accumulator, are .separate fromthe superheater tubes, i. e. the parts actuallyV serving the purpose ofsteam generation and lying in the ues. This makes it ossible todisconnect some parts entire y Without having to interrupt the operationof the plant and to provide the superheater tubes withv nonreturn valvesor valves which automatically disconnect a superheater tube from therest of the steam generator on a fracture occurring in the said tube.

For the same reason the steam generator may be Worked as a rapidevaporator and a peak boiler. The superheater tubes in which the steamis actually generated may be made of smaller diameter than the` Watertubes of ordinary steam boilers. Hence, the thickness of the Wall ofthese tubes may be small, even for high steam pressures. The Weightvofthe heating surfaces -is for this reason exceedingly small compared witha Water tube boiler having the same heating surface area. y The Waterspace and `the masses of the containers which in an ordinary boilerarerequired for containing these quantities of Water are also done awaywith. With suitable firing, for instance coal dust, the present steam.generator =can immediately commence to generate steam, as only the smallmasses of tubes of the superheater have to be brought up to the Workingtemperature, While the generation of steam commences immediately withthe injection of the Water into the super-heated steam. here steam isrequired immediately, the steam will in general be dravvn immediatelyfrom the evaporators andsuperheaters. When, however, the drum is underpressure or there is s'uiiicient time to bring it up to pressure, thesteam may be Withdrawn by Way of the said drum. Thus, the steamgenerator according to the present invention may be Worked, as required,as a tubular boiler pure and simple or, by connecting up theaccumulator-like steam collector, asa boilerY having a large Waterspace.

1n order to facilitate the mode of operation described above, it will beseen to that the drum is always under pressure, i. e. that the Water init is and remains at a temperature corresponding approximately to theWorking steam pressure. For this purpose, when shutting off the boiler,the remaining steam Will be passed into the Water space and duringworking a portion of the steam Will be allowed to pass through the Waterspace of the drum.

In order that, when starting up, it may not be necessary to Wait forexciter steam to be generated in the exciter boiler, the exciter steammay in many cases be Withdrawn from other sources, for instance boilershaving the same Working pressure which are in operation at the time. Afurther very useful method is the use of a so-called heat pump. Such aheat pump, more particularly When it should be a piston pump, makes itpossible, even When the contents of the drum are vconsiderably cooleddown, to obtain steam from the Water in the accumulator by suitablyreducing the pressure and to compress the same to the pressure requiredin the superheaters. The heat pump may thus render the exciter boilersuperfluous not only when starting' but also during normal Working.

In Fig. 6 the steam shown diagrammatically. The same parts have the samereference numerals as in Fig. l. Fig. 6 also shows the connection olithe pump for the injection Water, which is Withdrawn from the drum andthe motor for driving the pump. In addition to this, 7 5 is the suctionpipe for the heat pump Which itself has the reference numeral 76. '77vis the motor for driving theY pump. The figure also shows a connectingpipe 7 8 which can be shut olf by a valve 79 and enables excess n steamor thesteam generated after the Withdrawal of steam has ceased to beconveyed through all the superheaters and condensed in the Water spaceof the drum. As this Ygenerator is again lll drumin contradistinction tothe upper `drum of normal boilers is capable of Working With a veryvariable Water level, it is possible, for

instance when a large quantity of steam has i to be received by thedrum, to prevent an excessive increase in pressure by feeding in cooledWater.

Instead of being filled Withl Water the drum might also be filled Withliquid having a high boiling. point in order to obtain high temperaturesWith only a small pressure in the drum. Y In this case the superheatedsteam must flow in the interior in coils, Where it condenses and givesoff its heat to the liquid having a high boiling point. For generatingadditional steam or forV preheating the injection Water, Water is forcedthrough these coils and the stored heat is in this Way Withdrawn fromthe liquid having a high boiling point.

IVhatI claim is: f

l. In an apparatus of the class described, a steam and Water drum, aseries ofalternately connected'substantially dry evaporators andsuperheaters, an exciter boiler acting as an initial steam source anddelivering steam through a superheater into the first of saidevaporators, means for delivering Water from said steam and Water drumindividually and in finely divided form into said evaporators, means forreturning surplus Water from said evaporators to said steam and Waterdrum, and means for delivering steamv from the last of -said `series ofevaporators to a place of consumption. i

2. An apparatus as described in claim l, filling elements in saidevaporators adapted to distribute the Water. Y Y

3. In an apparatus as described in claim l, additional means fordeliveringwater individually into said evaporators from said exciterboiler. Y v

In testimony whereof I have signed my name to this specification.

WALTER GUSTAV NOACK.

